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Thu, March 14th, 2019 - 7:00AM
Fri, March 15th, 2019 - 7:00AM
Heather Thamm
Avalanche Warning
Issued: March 14, 2019 7:00 am
Travel in avalanche terrain is not recommended. Avoid being on or beneath all steep slopes.
Avalanche risk The Bottom Line

A BACKCOUNTRY AVALANCHE WARNING has been issued through the National Weather Service for the Turnagain Pass area and surrounding mountains.

Heavy snowfall and strong winds have created a HIGH avalanche danger in the mountains surrounding Turnagain Pass, Girdwood Valley, Portage Valley, and areas on the Kenai including Summit Lake and the Seward zone. Dangerous avalanche conditions are expected on all slopes 30 degrees and steeper – including runout zones. Avalanches are expected to release naturally, be easily triggered by people and send debris to valley floors. Travel in avalanche terrain is NOT recommended. Areas with steep slopes above should be avoided, such as the Byron Glacier Trail and the Seattle Ridge Uptrack. Even small terrain features could act as deadly traps.

Special Announcements
  • Our deepest condolences to the family and friends of two separate avalanche fatalities this week in Alaska. These are the first avalanche related deaths in Alaska this the winter. The first accident occurred on Saturday, March 9, near Crescent Saddle Cabin.  For a summary of what happened click HERE. We are working on a detailed report and will post it on our accidents pages under the resources tab soon. The most recent accident happened yesterday near Haines and details are limited at this time. We will keep you posted as information becomes available.
  • Today there will be intermittent traffic delays on the Seward Highway for Avalanche Hazard Reduction work From mile post 99 (Bird Flats) to mile post 86.5 (Kern Creek). Motorists should expect delays of up to 45 minutes between 9:00 and 2:00 PM.
  • Heading to Hatcher Pass? Be sure to check out the Hatcher Pass Avalanche Center mid-week snow and avalanche summary HERE.
Thu, March 14th, 2019
Above 2,500'
4 - High
Avalanche risk
4 - High
Avalanche risk
Below Treeline
Below 1,000'
4 - High
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Dangerous avalanche conditions. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
  • Certain
    Very Likely
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Likelihood of Avalanches
Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches
Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

Signal Word Size (D scale) Simple Descriptor
Small 1 Unlikely to bury a person
Large 2 Can bury a person
Very Large 3 Can destroy a house
Historic 4 & 5 Can destroy part or all of a village
More info at Avalanche.org

Today’s message is simple. Stay out of the mountains and avoid all avalanche terrain. Over the last 24 hours Turnagain pass has received 30 inches of new snow (2.4 inches SWE.) Alyeska mid way station in Girdwood has seen 19 inches. We expect similar if not more snow in the upper elevations of Portage Valley and the mountain surrounding Seward. Strong Easterly winds 40-60 mph occurred overnight and today’s winds will remain strong, 25-45 mph throughout the day. Another 6-12 inches of new snow is expected and another storm is on the horizon tomorrow, Friday. This afternoon winds will shift to the South bringing in warmer air and rain/snow line may increase to 1500 ft.

In the upper elevations expect large to very large dry avalanches to release naturally. Slab avalanches are expected to be 2-5+ feet deep and run long distances. In the lower elevations below 1000 ft, where rain is falling, wet avalanches are expected. The only way to manage this avalanche hazard is to stay well away from any avalanche terrain, slopes steeper than 30 degree and all runout zones. This includes giving Seattle Ridge plenty of space in the flats, as well avoiding any trails that go under avalanche terrain where it may be raining, like Bryon Glacier trail or the Bird to Gird Bike Path.

An active weather pattern will continue for Eastern Turnagain Arm tomorrow and into the weekend with several more storms headed this direction. The avalanche danger is expected to remain HIGH until this pattern changes and precipitation and winds back off.

South of Turnagain in Summit Lake where a variety of old weak layers (facets and buried surface hoar) sit in the mid and base of the snowpack, today’s rapid loading event is expected to cause natural avalanches. Although less snow has fallen than Turnagain, 1-2 feet of new snow is enough to tip the balance, not to mention strong winds. Expect natural avalanche activity throughout our entire Eastern Kenai Mountain region all the way to Seward.

Turnagain Pass DOT snow stake at the RWIS weather station (1000 ft) is showing over 3 feet of new since 3/12/19 at 9:30pm when this storm began. 

Photo taken yesterday in the Tincan trees with only 8″ of new snow. Small steep terrain features were releasing easily with the weight of a skier. This snow is releasing on a very slick melt freeze crust below 2500 ft. Now there is 3-4 feet of snow on this same bed surface. Small terrain features could be very dangerous today, even in places we often think of as safe, like Tincan trees. Photo by Andy Moterow.


Thu, March 14th, 2019

Yesterday: Snow showers favored Turnagain Pass and intensity increased overnight for total of 30 inches, (2.4 inches SWE) in 24 hours. In Girdwood precip was light most of the day until the evening and 19 inches of snow (1.0 inch of SWE) fell at Alyeska Mid way station. Ridgetop winds from the NE were 20-40mph range and increased in the evening with gusts in the 60-70s mph at Sunburst weather station. Temperature remained just above freezing at sea level overnight and low to mid-20s F near ridgetops. Rain/snow line is estimated around 500 ft overnight.

Today: A mix of rain and snow will continue throughout the day. In the upper elevations 6-12 inches is possible 0.4-0.9 inches rain below 1000 ft. Rain/snow line may reach 1500 ft mid-day. Ridge top winds will shift from the East to the South and decrease to 25-35mph with gusts in the 40s mph. Temperatures should remain in the mid to upper 20s F in the upper elevations.

Tomorrow: Heavy snow and rain is expected tomorrow as another storm tracks into our region. Strong Easterly ridgetop winds will continue throughout the day. Above freezing temperatures are expected in the lower elevations and may push into the mid elevations. Rain/snow line may be around 1500 ft. More storms are expected over the weekend and into next week.

*Seattle Ridge weather station is not reporting reliable wind data and the snow depth sensor at Summit Lake Snotel is not accurate as of 7am.

PRECIPITATION 24-hour data (6am – 6am)

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 30 30″ 2.4 100
Summit Lake (1400′) 31 ~14″ 0.7 *N/A
Alyeska Mid (1700′) 30 19″ 1.0 85

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 20   ENE   32   79  
Seattle Ridge (2400′) 26   *N/A   *N/A     *N/A    
Recent Observations for Turnagain Pass
Date Region Location
11/16/23 Turnagain Observation: Tincan Common
11/14/23 Turnagain Observation: Sunburst/Magnum
11/14/23 Turnagain Observation: Seattle Ridge
11/13/23 Turnagain Avalanche: Tincan Trees
11/12/23 Turnagain Observation: Sunburst
11/12/23 Turnagain Avalanche: Goldpan – avalanche
11/11/23 Turnagain Observation: Tincan Common
11/11/23 Turnagain Observation: Taylor Pass – Sunburst
11/10/23 Turnagain Observation: Tincan
11/10/23 Turnagain Observation: Tincan Trees
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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.